Synthesis for Thiazolidinedione Compounds

ABSTRACT

The present invention provides novel methods for synthesizing PPARγ sparing compounds, e.g., thiazolidinediones, that are useful for preventing and/or treating metabolic disorders such as diabetes, obesity, hypertension, and inflammatory diseases.

CROSS-REFERENCE TO RELATED APPLICATION

This PCT application claims the benefit of U.S. provisional applicationSer. No. 61/372,269, filed on Aug. 10, 2010, which is herebyincorporated by reference in its entirety.

TECHNICAL FIELD OF THE INVENTION

The present invention provides novel methods for synthesizing PPARγsparing compounds, e.g., thiazolidinediones, that are useful forpreventing and/or treating metabolic disorders such as diabetes,obesity, hypertension, dyslipidemia, and inflammatory diseases.

BACKGROUND OF THE INVENTION

Over the past several decades, scientists have postulated that PPARγ isthe generally accepted site of action for insulin sensitizingthiazolidinedione compounds.

Peroxisome Proliferator Activated Receptors (PPARs) are members of thenuclear hormone receptor super-family, which are ligand-activatedtranscription factors regulating gene expression. PPARs have beenimplicated in autoimmune diseases and other diseases, i.e., diabetesmellitus, cardiovascular and gastrointestinal disease, and Alzheimer'sdisease.

PPARγ is a key regulator of adipocyte differentiation and lipidmetabolism. PPARγ is also found in other cell types includingfibroblasts, myocytes, breast cells, human bone-marrow precursors, andmacrophages/monocytes. In addition, PPARγ has been shown in macrophagefoam cells in atherosclerotic plaques.

Thiazolidinediones, such as pioglitazone, developed originally for thetreatment of type-2 diabetes, generally exhibit high affinity as PPARγligands. The finding that thiazolidinediones might mediate theirtherapeutic effects through direct interactions with PPARγ helped toestablish the concept that PPARγ is a key regulator of glucose and lipidhomeostasis. However, compounds that involve the activation of PPARγ,such as pioglitazone, also trigger sodium reabsorption and otherunpleasant side effects.

SUMMARY OF THE INVENTION

In general, the invention relates to methods of synthesizing compoundsthat have reduced binding and activation of the nuclear transcriptionfactor PPARγ when compared with high affinity PPARγ ligands such aspioglitazone and rosiglitazone. These novel methods are scalable forindustrial production and employ safer, more stable, and/or less costlystarting materials and process conditions.

Compounds exhibiting PPARγ activity induce transcription of genes thatfavor sodium reabsorption. Advantageously, the compounds produced by thesyntheses of this invention have reduced binding or activation of thenuclear transcription factor PPARγ when compared with traditional highaffinity PPARγ ligands (e.g., pioglitazone or rosiglitazone), andtherefore produce fewer or diminished side effects (e.g., reducedaugmentation of sodium reabsorption) that are associated withtraditional high affinity PPARγ ligands, and are therefore more usefulin treating hypertension, dyslipidemia, diabetes, and inflammatorydiseases. Moreover, the reduced PPARγ binding and reduced activityexhibited by these compounds, as compared with traditional high affinityPPARγ ligands, are particularly useful for treating hypertension,diabetes, dyslipidemia, and inflammatory diseases both as single agentsand in combination with other classes of antihypertensive agents. Ashypertension and inflammatory diseases pose major risk factors in theonset of diabetes and pre-diabetes, these compounds are also useful forthe treatment and prevention of diabetes and other inflammatorydiseases. In fact, compounds synthesized by the present invention mayinduce remission of the symptoms of diabetes in a human patient.

One aspect of the present invention provides a novel synthesis forgenerating thiazolidine compounds that are useful for the treatment ofmetabolic disorders. This synthetic method is useful for preparing acompound of Formula I:

or a pharmaceutically acceptable salt thereof, wherein each of R₁ and R₂is independently selected from H, halo, aliphatic (e.g., C₁₋₆ alkyl), oralkoxy (e.g., C₁₋₆ alkoxy), wherein the aliphatic or alkoxy isoptionally substituted with 1-3 of halo; comprising the step ofconverting a compound of Formula 2A into a compound of Formula I

wherein R₃ is hydrogen or an optionally substituted C₁₋₆ alkyl. In someembodiments, the compound of Formula 2A undergoes hydrolysis to generatea compound of Formula I. In some examples, the compound of Formula 2A istreated with an acid to generate the compound of Formula I. In otherexamples, the compound of Formula 2A is treated with an acid and heat togenerate a compound of Formula I.

In some embodiments, R₃ is methyl, ethyl, propyl, isopropyl, butyl, ortert-butyl, each of which is optionally substituted. In otherembodiments, R₃ is methyl, ethyl, propyl, isopropyl, butyl, ortert-butyl, each of which is unsubstituted. And, in some embodiments, R₃is hydrogen.

Some embodiments further comprise reacting a compound of Formula 3A witha compound of Formula 4A:

wherein X₁ is a leaving group, to generate the compound of Formula 2A.In some embodiments, the compound of Formula 4A comprises

In other embodiments, the compound of Formula 4A comprises

And in some embodiments, the compound of Formula 4A comprises

Some embodiments further comprise converting a compound of Formula 5A

wherein X₁ is a leaving group, to a compound of Formula 4A. In someembodiments, X₁ is a halo (e.g., Cl or Br) or triflyl group.

In some embodiments, the compound of Formula 5A comprises

wherein X₁ is Cl or Br.

Some embodiments further comprise converting a compound of Formula 6A

to a compound of Formula 5A. For example, the compound of Formula 6Aundergoes halogenation to generate a compound of Formula 5A.

In some embodiments, the compound of Formula 6A comprises

wherein R₁ is selected from a C₁₋₆ alkyl or C₁₋₆ alkoxy, either of whichis optionally substituted with 1-3 halo, and R₂ is —H or halo.

In some embodiments, R₁ is a C₁₋₆ alkyl optionally substituted with 1-3halo. For example, R₁ is selected from methyl, ethyl, or propyl, any ofwhich is optionally substituted with 1-3 halo.

In some embodiments, the compound of Formula 6A comprises

Some embodiments further comprise reacting the compound

with the compound

under condensation conditions to form a compound of Formula 3B

and reducing the compound of Formula 3B to generate the compound ofFormula 3A.

Another aspect of the present invention provides compounds that areuseful in the methods of the present invention. One embodiment providesa compound of Formula 10A, 10B, or 10C

wherein R₁ is halo, C₁₋₆ alkyl optionally substituted with 1-3 halo, orC₁₋₆ alkoxy optionally substituted with 1-3 halo; R₃ is hydrogen orunsubstituted C₁₋₆ alkyl (e.g., unsubstituted C₁₋₄ alkyl); and X_(A) isa leaving group (e.g., halo or triflyl) or hydrogen.

Another aspect of the present invention provides a compound of Formula10D, 10E, or 10F

wherein R₁ and X_(A) are defined above.

In several embodiments, R₃ of Formula 10A, 10B, or 10C is hydrogen. Inother embodiments, R₃ of Formula 10A, 10B, or 10C is methyl, ethyl,propyl, isopropyl, butyl, or tert-butyl, each of which is unsubstituted.

Another aspect of the present invention provides a compound Formula11A-11M.

wherein X_(A) is a leaving group or hydrogen and R₃ is hydrogen or C₁₋₃unsubstituted alkyl.

In some embodiments, X_(A) is a leaving group selected from —Br, —Cl,—I, —OMs, —OTs, —OTf, —OBs, —ONs, —O-tresylate, or —OPO(OR₄)₂, whereineach R₄ is independently C₁₋₄ alkyl or two of R₄ together with theoxygen and phosphorous atoms to which they are attached form a 5-7membered ring. In other embodiments, X_(A) is hydrogen.

Another aspect of the present invention provides a compound of Formula2A

wherein each of R₁, R₂, and R₃ is defined above. For example, in oneembodiment, the compound of Formula 2A comprises

And, another aspect of the present invention provides a compoundselected from

wherein R₃ is defined above.

DETAILED DESCRIPTION

The present invention provides novel methods for preparingthiazolidinedione compounds having reduced PPARγ activity and compoundsuseful in these methods.

As used herein, the following definitions shall apply unless otherwiseindicated.

I. Definitions

For purposes of this invention, the chemical elements are identified inaccordance with the Periodic Table of the Elements, CAS version,Handbook of Chemistry and Physics, 75th Ed. Additionally, generalprinciples of organic chemistry are described in “Organic Chemistry”,Thomas Sorrell, University Science Books, Sausalito: 1999, and “March'sAdvanced Organic Chemistry”, 5th Ed., Ed.: Smith, M. B. and March, J.,John Wiley & Sons, New York: 2001, the entire contents of which arehereby incorporated by reference.

As described herein, “protecting group” refers to a moiety orfunctionality that is introduced into a molecule by chemicalmodification of a functional group in order to obtain chemoselectivityin a subsequent chemical reaction. Standard protecting groups areprovided in Greene and Wuts : “Greene's Protective Groups in OrganicSynthesis” 4th Ed, Wuts, P. G. M. and Greene, T. W., Wiley-Interscience,New York:2006.

As described herein, compounds of the invention may optionally besubstituted with one or more substituents, such as are illustratedgenerally above, or as exemplified by particular classes, subclasses,and species of the invention.

As used herein, the term “hydroxyl” or “hydroxy” refers to an —OHmoiety.

As used herein the term “aliphatic” encompasses the terms alkyl,alkenyl, alkynyl, each of which being optionally substituted as setforth below.

As used herein, an “alkyl” group refers to a saturated aliphatichydrocarbon group containing 1-12 (e.g., 1-8, 1-6, or 1-4) carbon atoms.An alkyl group can be straight or branched. Examples of alkyl groupsinclude, but are not limited to, methyl, ethyl, propyl, isopropyl,butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-heptyl, or2-ethylhexyl. An alkyl group can be substituted (i.e., optionallysubstituted) with one or more substituents such as halo, phospho,cycloaliphatic [e.g., cycloalkyl or cycloalkenyl], heterocycloaliphatic[e.g., heterocycloalkyl or heterocycloalkenyl], aryl, heteroaryl,alkoxy, aroyl, heteroaroyl, acyl [e.g., (aliphatic)carbonyl,(cycloaliphatic)carbonyl, or (heterocycloaliphatic)carbonyl], nitro,cyano, amido [e.g., (cycloalkylalkyl)carbonylamino, arylcarbonylamino,aralkylcarbonylamino, (heterocycloalkyl)carbonylamino,(heterocycloalkylalkyl)carbonylamino, heteroarylcarbonylamino,heteroaralkylcarbonylamino alkylaminocarbonyl, cycloalkylaminocarbonyl,heterocycloalkylaminocarbonyl, arylaminocarbonyl, orheteroarylaminocarbonyl], amino [e.g., aliphaticamino,cycloaliphaticamino, or heterocycloaliphaticamino], sulfonyl [e.g.,aliphatic-SO₂—], sulfinyl, sulfanyl, sulfoxy, urea, thiourea, sulfamoyl,sulfamide, oxo, carboxy, carbamoyl, cycloaliphaticoxy,heterocycloaliphaticoxy, aryloxy, heteroaryloxy, aralkyloxy,heteroarylalkoxy, alkoxycarbonyl, alkylcarbonyloxy, or hydroxy. Withoutlimitation, some examples of substituted alkyls include carboxyalkyl(such as HOOC-alkyl, alkoxycarbonylalkyl, and alkylcarbonyloxyalkyl),cyanoalkyl, hydroxyalkyl, alkoxyalkyl, acylalkyl, aralkyl,(alkoxyaryl)alkyl, (sulfonylamino)alkyl (such as(alkyl-SO₂-amino)alkyl), aminoalkyl, amidoalkyl, (cycloaliphatic)alkyl,or haloalkyl.

As used herein, an “alkenyl” group refers to an aliphatic carbon groupthat contains 2-8 (e.g., 2-12, 2-6, or 2-4) carbon atoms and at leastone double bond. Like an alkyl group, an alkenyl group can be straightor branched. Examples of an alkenyl group include, but are not limitedto allyl, isoprenyl, 2-butenyl, and 2-hexenyl. An alkenyl group can beoptionally substituted with one or more substituents such as halo,phospho, cycloaliphatic [e.g., cycloalkyl or cycloalkenyl],heterocycloaliphatic [e.g., heterocycloalkyl or heterocycloalkenyl],aryl, heteroaryl, alkoxy, aroyl, heteroaroyl, acyl [e.g.,(aliphatic)carbonyl, (cycloaliphatic)carbonyl, or(heterocycloaliphatic)carbonyl], nitro, cyano, amido [e.g.,(cycloalkylalkyl)carbonylamino, arylcarbonylamino, aralkylcarbonylamino,(heterocycloalkyl)carbonylamino, (heterocycloalkylalkyl)carbonylamino,heteroarylcarbonylamino, heteroaralkylcarbonylamino alkylaminocarbonyl,cycloalkylaminocarbonyl, heterocycloalkylaminocarbonyl,arylaminocarbonyl, or heteroarylaminocarbonyl], amino [e.g.,aliphaticamino, cycloaliphaticamino, heterocycloaliphaticamino, oraliphaticsulfonylamino], sulfonyl [e.g., alkyl-SO₂—,cycloaliphatic-SO₂—, or aryl-SO₂—], sulfinyl, sulfanyl, sulfoxy, urea,thiourea, sulfamoyl, sulfamide, oxo, carboxy, carbamoyl,cycloaliphaticoxy, heterocycloaliphaticoxy, aryloxy, heteroaryloxy,aralkyloxy, heteroaralkoxy, alkoxycarbonyl, alkylcarbonyloxy, orhydroxy. Without limitation, some examples of substituted alkenylsinclude cyanoalkenyl, alkoxyalkenyl, acylalkenyl, hydroxyalkenyl,aralkenyl, (alkoxyaryl)alkenyl, (sulfonylamino)alkenyl (such as(alkyl-SO₂-amino)alkenyl), aminoalkenyl, amidoalkenyl,(cycloaliphatic)alkenyl, or haloalkenyl.

As used herein, an “alkynyl” group refers to an aliphatic carbon groupthat contains 2-8 (e.g., 2-12, 2-6, or 2-4) carbon atoms and has atleast one triple bond. An alkynyl group can be straight or branched.Examples of an alkynyl group include, but are not limited to, propargyland butynyl. An alkynyl group can be optionally substituted with one ormore substituents such as aroyl, heteroaroyl, alkoxy, cycloalkyloxy,heterocycloalkyloxy, aryloxy, heteroaryloxy, aralkyloxy, nitro, carboxy,cyano, halo, hydroxy, sulfo, mercapto, sulfanyl [e.g., aliphaticsulfanylor cycloaliphaticsulfanyl], sulfinyl [e.g., aliphaticsulfinyl orcycloaliphaticsulfinyl], sulfonyl [e.g., aliphatic-SO₂—,aliphaticamino-SO₂—, or cycloaliphatic-SO₂—], amido [e.g.,aminocarbonyl, alkylaminocarbonyl, alkylcarbonylamino,cycloalkylaminocarbonyl, heterocycloalkylaminocarbonyl,cycloalkylcarbonylamino, arylaminocarbonyl, arylcarbonylamino,aralkylcarbonylamino, (heterocycloalkyl)carbonylamino,(cycloalkylalkyl)carbonylamino, heteroaralkylcarbonylamino,heteroarylcarbonylamino or heteroarylaminocarbonyl], urea, thiourea,sulfamoyl, sulfamide, alkoxycarbonyl, alkylcarbonyloxy, cycloaliphatic,heterocycloaliphatic, aryl, heteroaryl, acyl [e.g.,(cycloaliphatic)carbonyl or (heterocycloaliphatic)carbonyl], amino[e.g., aliphaticamino], sulfoxy, oxo, carboxy, carbamoyl,(cycloaliphatic)oxy, (heterocycloaliphatic)oxy, or (heteroaryl)alkoxy.

As used herein, an “amido” encompasses both “aminocarbonyl” and“carbonylamino”. These terms when used alone or in connection withanother group refer to an amido group such as —N(R^(X))—C(O)—R^(Y) or—C(O)—N(R^(X))₂, when used terminally, and —C(O)—N(R^(X))— or—N(R^(X))—C(O)— when used internally, wherein R^(X) and R^(Y) can bealiphatic, cycloaliphatic, aryl, araliphatic, heterocycloaliphatic,heteroaryl or heteroaraliphatic. Examples of amido groups includealkylamido (such as alkylcarbonylamino or alkylaminocarbonyl),(heterocycloaliphatic)amido, (heteroaralkyl)amido, (heteroaryl)amido,(heterocycloalkyl)alkylamido, arylamido, aralkylamido,(cycloalkyl)alkylamido, or cycloalkylamido.

As used herein, an “amino” group refers to —NR^(X)R^(Y) wherein each ofR^(X) and R^(Y) is independently hydrogen, aliphatic, cycloaliphatic,(cycloaliphatic)aliphatic, aryl, araliphatic, heterocycloaliphatic,(heterocycloaliphatic)aliphatic, heteroaryl, carboxy, sulfanyl,sulfinyl, sulfonyl, (aliphatic)carbonyl, (cycloaliphatic)carbonyl,((cycloaliphatic)aliphatic)carbonyl, arylcarbonyl,(araliphatic)carbonyl, (heterocycloaliphatic)carbonyl,((heterocycloaliphatic)aliphatic)carbonyl, (heteroaryl)carbonyl, or(heteroaraliphatic)carbonyl, each of which being defined herein andbeing optionally substituted. Examples of amino groups includealkylamino, dialkylamino, or arylamino. When the term “amino” is not theterminal group (e.g., alkylcarbonylamino), it is represented by—NR^(X)—, where R^(X) has the same meaning as defined above.

As used herein, an “aryl” group used alone or as part of a larger moietyas in “aralkyl”, “aralkoxy”, or “aryloxyalkyl” refers to monocyclic(e.g., phenyl); bicyclic (e.g., indenyl, naphthalenyl,tetrahydronaphthyl, tetrahydroindenyl); and tricyclic (e.g., fluorenyltetrahydrofluorenyl, or tetrahydroanthracenyl, anthracenyl) ring systemsin which the monocyclic ring system is aromatic or at least one of therings in a bicyclic or tricyclic ring system is aromatic. The bicyclicand tricyclic groups include benzofused 2-3 membered carbocyclic rings.For example, a benzofused group includes phenyl fused with two or moreC₄₋₈ carbocyclic moieties. An aryl is optionally substituted with one ormore substituents including aliphatic [e.g., alkyl, alkenyl, oralkynyl]; cycloaliphatic; (cycloaliphatic)aliphatic;heterocycloaliphatic; (heterocycloaliphatic)aliphatic; aryl; heteroaryl;alkoxy; (cycloaliphatic)oxy; (heterocycloaliphatic)oxy; aryloxy;heteroaryloxy; (araliphatic)oxy; (heteroaraliphatic)oxy; aroyl;heteroaroyl; amino; oxo (on a non-aromatic carbocyclic ring of abenzofused bicyclic or tricyclic aryl); nitro; carboxy; amido; acyl[e.g., (aliphatic)carbonyl; (cycloaliphatic)carbonyl;((cycloaliphatic)aliphatic)carbonyl; (araliphatic)carbonyl;(heterocycloaliphatic)carbonyl;((heterocycloaliphatic)aliphatic)carbonyl; or(heteroaraliphatic)carbonyl]; sulfonyl [e.g., aliphatic-SO₂— oramino-SO₂—; sulfinyl [e.g., aliphatic-S(O)— or cycloaliphatic-S(O)—];sulfanyl [e.g., aliphatic-S—]; cyano; halo; hydroxy; mercapto; sulfoxy;urea; thiourea; sulfamoyl; sulfamide; or carbamoyl. Alternatively, anaryl can be unsubstituted.

Non-limiting examples of substituted aryls include haloaryl [e.g.,mono-, di (such as p,m-dihaloaryl), and (trihalo)aryl]; (carboxy)aryl[e.g., (alkoxycarbonyl)aryl, ((aralkyl)carbonyloxy)aryl, and(alkoxycarbonyl)aryl]; (amido)aryl [e.g., (aminocarbonyl)aryl,(((alkylamino)alkyl)aminocarbonyl)aryl, (alkylcarbonyl)aminoaryl,(arylaminocarbonyl)aryl, and (((heteroaryl)amino)carbonyl)aryl];aminoaryl [e.g., ((alkylsulfonyl)amino)aryl or ((dialkyl)amino)aryl];(cyanoalkyl)aryl; (alkoxy)aryl; (sulfamoyl)aryl [e.g.,(aminosulfonyl)aryl]; (alkylsulfonyl)aryl; (cyano)aryl;(hydroxyalkyl)aryl; ((alkoxy)alkyl)aryl; (hydroxy)aryl,((carboxy)alkyl)aryl; (((dialkyl)amino)alkyl)aryl; (nitroalkyl)aryl;(((alkylsulfonyl)amino)alkyl)aryl; ((heterocycloaliphatic)carbonyl)aryl;((alkylsulfonyl)alkyl)aryl; (cyanoalkyl)aryl; (hydroxyalkyl)aryl;(alkylcarbonyl)aryl; alkylaryl; (trihaloalkyl)aryl;p-amino-m-alkoxycarbonylaryl; p-amino-m-cyanoaryl; p-halo-m-aminoaryl;or (m-(heterocycloaliphatic)-o-(alkyl))aryl.

As used herein, an “araliphatic” such as an “aralkyl” group refers to analiphatic group (e.g., a C₁₋₄ alkyl group) that is substituted with anaryl group. “Aliphatic,” “alkyl,” and “aryl” are defined herein. Anexample of an araliphatic such as an aralkyl group is benzyl.

As used herein, an “aralkyl” group refers to an alkyl group (e.g., aC₁₋₄ alkyl group) that is substituted with an aryl group. Both “alkyl”and “aryl” have been defined above. An example of an aralkyl group isbenzyl. An aralkyl is optionally substituted with one or moresubstituents such as aliphatic [e.g., alkyl, alkenyl, or alkynyl,including carboxyalkyl, hydroxyalkyl, or haloalkyl such astrifluoromethyl], cycloaliphatic [e.g., cycloalkyl or cycloalkenyl],(cycloalkyl)alkyl, heterocycloalkyl, (heterocycloalkyl)alkyl, aryl,heteroaryl, alkoxy, cycloalkyloxy, heterocycloalkyloxy, aryloxy,heteroaryloxy, aralkyloxy, heteroaralkyloxy, aroyl, heteroaroyl, nitro,carboxy, alkoxycarbonyl, alkylcarbonyloxy, amido [e.g., aminocarbonyl,alkylcarbonylamino, cycloalkylcarbonylamino,(cycloalkylalkyl)carbonylamino, arylcarbonylamino, aralkylcarbonylamino,(heterocycloalkyl)carbonylamino, (heterocycloalkylalkyl)carbonylamino,heteroarylcarbonylamino, or heteroaralkylcarbonylamino], cyano, halo,hydroxy, acyl, mercapto, alkylsulfanyl, sulfoxy, urea, thiourea,sulfamoyl, sulfamide, oxo, or carbamoyl.

As used herein, a “bicyclic ring system” includes 8-12 (e.g., 9, 10, or11) membered structures that form two rings, wherein the two rings haveat least one atom in common (e.g., 2 atoms in common). Bicyclic ringsystems include bicycloaliphatics (e.g., bicycloalkyl orbicycloalkenyl), bicycloheteroaliphatics, bicyclic aryls, and bicyclicheteroaryls.

As used herein, a “cycloaliphatic” group encompasses a “cycloalkyl”group and a “cycloalkenyl” group, each of which being optionallysubstituted as set forth below.

As used herein, a “cycloalkyl” group refers to a saturated carbocyclicmono- or bicyclic (fused or bridged) ring of 3-10 (e.g., 5-10) carbonatoms. Examples of cycloalkyl groups include cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, adamantyl, norbornyl, cubyl,octahydro-indenyl, decahydro-naphthyl, bicyclo[3.2.1]octyl,bicyclo[2.2.2]octyl, bicyclo[3.3.1]nonyl, bicyclo[3.3.2.]decyl,bicyclo[2.2.2]octyl, adamantyl, or((aminocarbonyl)cycloalkyl)cycloalkyl.

A “cycloalkenyl” group, as used herein, refers to a non-aromaticcarbocyclic ring of 3-10 (e.g., 4-8) carbon atoms having one or moredouble bonds. Examples of cycloalkenyl groups include cyclopentenyl,1,4-cyclohexa-di-enyl, cycloheptenyl, cyclooctenyl, hexahydro-indenyl,octahydro-naphthyl, cyclohexenyl, cyclopentenyl, bicyclo[2.2.2]octenyl,or bicyclo[3.3.1]nonenyl.

A cycloalkyl or cycloalkenyl group can be optionally substituted withone or more substituents such as phosphor, aliphatic [e.g., alkyl,alkenyl, or alkynyl], cycloaliphatic, (cycloaliphatic) aliphatic,heterocycloaliphatic, (heterocycloaliphatic) aliphatic, aryl,heteroaryl, alkoxy, (cycloaliphatic)oxy, (heterocycloaliphatic)oxy,aryloxy, heteroaryloxy, (araliphatic)oxy, (heteroaraliphatic)oxy, aroyl,heteroaroyl, amino, amido [e.g., (aliphatic)carbonylamino,(cycloaliphatic)carbonylamino, ((cycloaliphatic)aliphatic)carbonylamino,(aryl)carbonylamino, (araliphatic)carbonylamino,(heterocycloaliphatic)carbonylamino,((heterocycloaliphatic)aliphatic)carbonylamino,(heteroaryl)carbonylamino, or (heteroaraliphatic)carbonylamino], nitro,carboxy [e.g., HOOC—, alkoxycarbonyl, or alkylcarbonyloxy], acyl [e.g.,(cycloaliphatic)carbonyl, ((cycloaliphatic) aliphatic)carbonyl,(araliphatic)carbonyl, (heterocycloaliphatic)carbonyl,((heterocycloaliphatic)aliphatic)carbonyl, or(heteroaraliphatic)carbonyl], cyano, halo, hydroxy, mercapto, sulfonyl[e.g., alkyl-SO₂— and aryl-SO₂—], sulfinyl [e.g., alkyl-S(O)—], sulfanyl[e.g., alkyl-S—], sulfoxy, urea, thiourea, sulfamoyl, sulfamide, oxo, orcarbamoyl.

As used herein, the term “heterocycloaliphatic” encompassesheterocycloalkyl groups and heterocycloalkenyl groups, each of whichbeing optionally substituted as set forth below.

As used herein, a “heterocycloalkyl” group refers to a 3-10 memberedmono- or bicylic (fused or bridged) (e.g., 5- to 10-membered mono- orbicyclic) saturated ring structure, in which one or more of the ringatoms is a heteroatom (e.g., N, O, S, or combinations thereof). Examplesof a heterocycloalkyl group include piperidyl, piperazyl,tetrahydropyranyl, tetrahydrofuryl, 1,4-dioxolanyl, 1,4-dithianyl,1,3-dioxolanyl, oxazolidyl, isoxazolidyl, morpholinyl, thiomorpholyl,octahydrobenzofuryl, octahydrochromenyl, octahydrothiochromenyl,octahydroindolyl, octahydropyrindinyl, decahydroquinolinyl,octahydrobenzo[b]thiopheneyl, 2-oxa-bicyclo[2.2.2]octyl,1-aza-bicyclo[2.2.2]octyl, 3-aza-bicyclo[3.2.1]octyl, and2,6-dioxa-tricyclo[3.3.1.0^(3.7)]nonyl. A monocyclic heterocycloalkylgroup can be fused with a phenyl moiety to form structures, such astetrahydroisoquinoline, which would be categorized as heteroaryls.

A “heterocycloalkenyl” group, as used herein, refers to a mono- orbicylic (e.g., 5- to 10-membered mono- or bicyclic) non-aromatic ringstructure having one or more double bonds, and wherein one or more ofthe ring atoms is a heteroatom (e.g., N, O, or S). Monocyclic andbicyclic heterocycloaliphatics are numbered according to standardchemical nomenclature.

A heterocycloalkyl or heterocycloalkenyl group can be optionallysubstituted with one or more substituents such as phosphor, aliphatic[e.g., alkyl, alkenyl, or alkynyl], cycloaliphatic,(cycloaliphatic)aliphatic, heterocycloaliphatic,(heterocycloaliphatic)aliphatic, aryl, heteroaryl, alkoxy,(cycloaliphatic)oxy, (heterocycloaliphatic)oxy, aryloxy, heteroaryloxy,(araliphatic)oxy, (heteroaraliphatic)oxy, aroyl, heteroaroyl, amino,amido [e.g., (aliphatic)carbonylamino, (cycloaliphatic)carbonylamino,((cycloaliphatic) aliphatic)carbonylamino, (aryl)carbonylamino,(araliphatic)carbonylamino, (heterocycloaliphatic)carbonylamino,((heterocycloaliphatic) aliphatic)carbonylamino,(heteroaryl)carbonylamino, or (heteroaraliphatic)carbonylamino], nitro,carboxy [e.g., HOOC—, alkoxycarbonyl, or alkylcarbonyloxy], acyl [e.g.,(cycloaliphatic)carbonyl, ((cycloaliphatic) aliphatic)carbonyl,(araliphatic)carbonyl, (heterocycloaliphatic)carbonyl,((heterocycloaliphatic)aliphatic)carbonyl, or(heteroaraliphatic)carbonyl], nitro, cyano, halo, hydroxy, mercapto,sulfonyl [e.g., alkylsulfonyl or arylsulfonyl], sulfinyl [e.g.,alkylsulfinyl], sulfanyl [e.g., alkylsulfanyl], sulfoxy, urea, thiourea,sulfamoyl, sulfamide, oxo, or carbamoyl.

A “heteroaryl” group, as used herein, refers to a monocyclic, bicyclic,or tricyclic ring system having 4 to 15 ring atoms wherein one or moreof the ring atoms is a heteroatom (e.g., N, O, S, or combinationsthereof) and in which the monocyclic ring system is aromatic or at leastone of the rings in the bicyclic or tricyclic ring systems is aromatic.A heteroaryl group includes a benzofused ring system having 2 to 3rings. For example, a benzofused group includes benzo fused with one ortwo 4 to 8 membered heterocycloaliphatic moieties (e.g., indolizyl,indolyl, isoindolyl, 3H-indolyl, indolinyl, benzo[b]furyl,benzo[b]thiophenyl, quinolinyl, or isoquinolinyl). Some examples ofheteroaryl are pyridyl, 1H-indazolyl, furyl, pyrrolyl, thienyl,thiazolyl, oxazolyl, imidazolyl, tetrazolyl, benzofuryl, isoquinolinyl,benzthiazolyl, xanthene, thioxanthene, phenothiazine, dihydroindole,benzo[1,3]dioxole, benzo[b]furyl, benzo[b]thiophenyl, indazolyl,benzimidazolyl, benzthiazolyl, puryl, cinnolyl, quinolyl,quinazolyl,cinnolyl, phthalazyl, quinazolyl, quinoxalyl, isoquinolyl,4H-quinolizyl, benzo-1,2,5-thiadiazolyl, or 1,8-naphthyridyl.

Without limitation, monocyclic heteroaryls include furyl, thiophenyl,2H-pyrrolyl, pyrrolyl, oxazolyl, thazolyl, imidazolyl, pyrazolyl,isoxazolyl, isothiazolyl, 1,3,4-thiadiazolyl, 2H-pyranyl, 4-H-pranyl,pyridyl, pyridazyl, pyrimidyl, pyrazolyl, pyrazyl, or 1,3,5-triazyl.Monocyclic heteroaryls are numbered according to standard chemicalnomenclature.

Without limitation, bicyclic heteroaryls include indolizyl, indolyl,isoindolyl, 3H-indolyl, indolinyl, benzo[b]furyl, benzo[b]thiophenyl,quinolinyl, isoquinolinyl, indolizyl, isoindolyl, indolyl,benzo[b]furyl, bexo[b]thiophenyl, indazolyl, benzimidazyl,benzthiazolyl, purinyl, 4H-quinolizyl, quinolyl, isoquinolyl, cinnolyl,phthalazyl, quinazolyl, quinoxalyl, 1,8-naphthyridyl, or pteridyl.Bicyclic heteroaryls are numbered according to standard chemicalnomenclature.

A heteroaryl is optionally substituted with one or more substituentssuch as aliphatic [e.g., alkyl, alkenyl, or alkynyl]; cycloaliphatic;(cycloaliphatic)aliphatic; heterocycloaliphatic;(heterocycloaliphatic)aliphatic; aryl; heteroaryl; alkoxy;(cycloaliphatic)oxy; (heterocycloaliphatic)oxy; aryloxy; heteroaryloxy;(araliphatic)oxy; (heteroaraliphatic)oxy; aroyl; heteroaroyl; amino; oxo(on a non-aromatic carbocyclic or heterocyclic ring of a bicyclic ortricyclic heteroaryl); carboxy; amido; acyl [e.g., aliphaticcarbonyl;(cycloaliphatic)carbonyl; ((cycloaliphatic)aliphatic)carbonyl;(araliphatic)carbonyl; (heterocycloaliphatic)carbonyl;((heterocycloaliphatic)aliphatic)carbonyl; or(heteroaraliphatic)carbonyl]; sulfonyl [e.g., aliphaticsulfonyl oraminosulfonyl]; sulfinyl [e.g., aliphaticsulfinyl]; sulfanyl [e.g.,aliphaticsulfanyl]; nitro; cyano; halo; hydroxy; mercapto; sulfoxy;urea; thiourea; sulfamoyl; sulfamide; or carbamoyl. Alternatively, aheteroaryl can be unsubstituted.

Non-limiting examples of substituted heteroaryls include(halo)heteroaryl [e.g., mono- and di-(halo)heteroaryl];(carboxy)heteroaryl [e.g., (alkoxycarbonyl)heteroaryl]; cyanoheteroaryl;aminoheteroaryl [e.g., ((alkylsulfonyl)amino)heteroaryl and((dialkyl)amino)heteroaryl]; (amido)heteroaryl [e.g.,aminocarbonylheteroaryl, ((alkylcarbonyl)amino)heteroaryl,((((alkyl)amino)alkyl)aminocarbonyl)heteroaryl,(((heteroaryl)amino)carbonyl)heteroaryl,((heterocycloaliphatic)carbonyl)heteroaryl, and((alkylcarbonyl)amino)heteroaryl]; (cyanoalkyl)heteroaryl;(alkoxy)heteroaryl; (sulfamoyl)heteroaryl [e.g.,(aminosulfonyl)heteroaryl]; (sulfonyl)heteroaryl [e.g.,(alkylsulfonyl)heteroaryl]; (hydroxyalkyl)heteroaryl;(alkoxyalkyl)heteroaryl; (hydroxy)heteroaryl;((carboxy)alkyl)heteroaryl; (((dialkyl)amino)alkyl]heteroaryl;(heterocycloaliphatic)heteroaryl; (cycloaliphatic)heteroaryl;(nitroalkyl)heteroaryl; (((alkylsulfonyl)amino)alkyl)heteroaryl;((alkylsulfonyl)alkyl)heteroaryl; (cyanoalkyl)heteroaryl;(acyl)heteroaryl [e.g., (alkylcarbonyl)heteroaryl]; (alkyl)heteroaryl;or (haloalkyl)heteroaryl [e.g., trihaloalkylheteroaryl].

A “heteroaraliphatic” (such as a heteroaralkyl group) as used herein,refers to an aliphatic group (e.g., a C₁₋₄ alkyl group) that issubstituted with a heteroaryl group. “Aliphatic”, “alkyl”, and“heteroaryl” have been defined above.

A “heteroaralkyl” group, as used herein, refers to an alkyl group (e.g.,a C₁₋₄ alkyl group) that is substituted with a heteroaryl group. Both“alkyl” and “heteroaryl” have been defined above. A heteroaralkyl isoptionally substituted with one or more substituents such as alkyl(including carboxyalkyl, hydroxyalkyl, and haloalkyl such astrifluoromethyl), alkenyl, alkynyl, cycloalkyl, (cycloalkyl)alkyl,heterocycloalkyl, (heterocycloalkyl)alkyl, aryl, heteroaryl, alkoxy,cycloalkyloxy, heterocycloalkyloxy, aryloxy, heteroaryloxy, aralkyloxy,heteroaralkyloxy, aroyl, heteroaroyl, nitro, carboxy, alkoxycarbonyl,alkylcarbonyloxy, aminocarbonyl, alkylcarbonylamino,cycloalkylcarbonylamino, (cycloalkylalkyl)carbonylamino,arylcarbonylamino, aralkylcarbonylamino,(heterocycloalkyl)carbonylamino, (heterocycloalkylalkyl)carbonylamino,heteroarylcarbonylamino, heteroaralkylcarbonylamino, cyano, halo,hydroxy, acyl, mercapto, alkylsulfanyl, sulfoxy, urea, thiourea,sulfamoyl, sulfamide, oxo, or carbamoyl.

As used herein, “cyclic moiety” and “cyclic group” refer to mono-, bi-,and tri-cyclic ring systems including cycloaliphatic,heterocycloaliphatic, aryl, or heteroaryl, each of which has beenpreviously defined.

As used herein, a “bridged bicyclic ring system” refers to a bicyclicheterocyclicalipahtic ring system or bicyclic cycloaliphatic ring systemin which the rings are bridged. Examples of bridged bicyclic ringsystems include, but are not limited to, adamantanyl, norbornanyl,bicyclo[3.2.1]octyl, bicyclo[2.2.2]octyl, bicyclo[3.3.1]nonyl,bicyclo[3.3.2]decyl, 2-oxabicyclo[2.2.2]octyl, 1-azabicyclo[2.2.2]octyl,3-azabicyclo[3.2.1]octyl, and 2,6-dioxatricyclo[3.3.1.0^(3.7)]nonyl. Abridged bicyclic ring system can be optionally substituted with one ormore substituents such as alkyl (including carboxyalkyl, hydroxyalkyl,and haloalkyl such as trifluoromethyl), alkenyl, alkynyl, cycloalkyl,(cycloalkyl)alkyl, heterocycloalkyl, (heterocycloalkyl)alkyl, aryl,heteroaryl, alkoxy, cycloalkyloxy, heterocycloalkyloxy, aryloxy,heteroaryloxy, aralkyloxy, heteroaralkyloxy, aroyl, heteroaroyl, nitro,carboxy, alkoxycarbonyl, alkylcarbonyloxy, aminocarbonyl,alkylcarbonylamino, cycloalkylcarbonylamino,(cycloalkylalkyl)carbonylamino, arylcarbonylamino, aralkylcarbonylamino,(heterocycloalkyl)carbonylamino, (heterocycloalkylalkyl)carbonylamino,heteroarylcarbonylamino, heteroaralkylcarbonylamino, cyano, halo,hydroxy, acyl, mercapto, alkylsulfanyl, sulfoxy, urea, thiourea,sulfamoyl, sulfamide, oxo, or carbamoyl.

As used herein, an “acyl” group refers to a formyl group or R^(X)—C(O)—(such as alkyl-C(O)—, also referred to as “alkylcarbonyl”) where R^(X)and “alkyl” have been defined previously. Acetyl and pivaloyl areexamples of acyl groups.

As used herein, an “aroyl” or “heteroaroyl” refers to an aryl-C(O)— or aheteroaryl-C(O)—. The aryl and heteroaryl portion of the aroyl orheteroaroyl is optionally substituted as previously defined.

As used herein, an “alkoxy” group refers to an alkyl-O— group where“alkyl” has been defined previously.

As used herein, a “carbamoyl” group refers to a group having thestructure —O—CO—NR^(X)R^(Y) or —NR^(X)—CO—O—R^(Z), wherein R^(X) andR^(Y) have been defined above and R^(Z) can be aliphatic, aryl,araliphatic, heterocycloaliphatic, heteroaryl, or heteroaraliphatic.

As used herein, a “carboxy” group refers to —COOH, —COOR^(X), —OC(O)H,—OC(O)R^(X), when used as a terminal group; or —OC(O)— or —C(O)O— whenused as an internal group.

As used herein, a “haloaliphatic” group refers to an aliphatic groupsubstituted with 1-3 halogen. For instance, the term haloalkyl includesthe group —CF₃.

As used herein, a “mercapto” group refers to —SH.

As used herein, a “sulfo” group refers to —SO₃H or —SO₃R^(X) when usedterminally or —S(O)₃— when used internally.

As used herein, a “sulfamide” group refers to the structure—NR^(X)—S(O)₂—NR^(Y)R^(Z) when used terminally and —NR^(X)—S(O)₂—NR^(Y)—when used internally, wherein R^(X), R^(Y), and R^(Z) have been definedabove.

As used herein, a “sulfamoyl” group refers to the structure—O—S(O)₂—NR^(Y)R^(Z) wherein R^(Y) and R^(Z) have been defined above.

As used herein, a “sulfonamide” group refers to the structure—S(O)₂—NR^(X)R^(Y) or —NR^(X)—S(O)₂—R^(Z) when used terminally; or—S(O)₂—NR^(X)— or —NR^(X)—S(O)₂— when used internally, wherein R^(X),R^(Y), and R^(Z) are defined above.

As used herein a “sulfanyl” group refers to —S—R^(X) when usedterminally and —S— when used internally, wherein R^(X) has been definedabove. Examples of sulfanyls include aliphatic-S—, cycloaliphatic-S—,aryl-S—, or the like.

As used herein a “sulfinyl” group refers to —S(O)—R^(X) when usedterminally and —S(O)— when used internally, wherein R^(X) has beendefined above. Exemplary sulfinyl groups include aliphatic-S(O)—,aryl-S(O)—, (cycloaliphatic(aliphatic))-S(O)—, cycloalkyl-S(O)—,heterocycloaliphatic-S(O)—, heteroaryl-S(O)—, or the like.

As used herein, a “sulfonyl” group refers to —S(O)₂—R^(X) when usedterminally and —S(O)₂— when used internally, wherein R^(X) has beendefined above. Exemplary sulfonyl groups include aliphatic-S(O)₂—,aryl-S(O)₂—, (cycloaliphatic(aliphatic))-S(O)₂—, cycloaliphatic-S(O)₂—,heterocycloaliphatic-S(O)₂—, heteroaryl-S(O)₂—,(cycloaliphatic(amido(aliphatic)))-S(O)₂— or the like.

As used herein, a “sulfoxy” group refers to —O—SO—R^(X) or —SO—O—R^(X),when used terminally and —O—S(O)— or —S(O)—O— when used internally,where R^(X) has been defined above.

As used herein, a “halogen” or “halo” group refers to fluorine,chlorine, bromine or iodine.

As used herein, an “alkoxycarbonyl,” which is encompassed by the termcarboxy, used alone or in connection with another group refers to agroup such as alkyl-O—C(O)—.

As used herein, an “alkoxyalkyl” refers to an alkyl group such asalkyl-O-alkyl-, wherein alkyl has been defined above.

As used herein, a “carbonyl” refer to —C(O)—.

As used herein, an “oxo” refers to ═0.

As used herein, the term “phospho” refers to phosphinates andphosphonates. Examples of phosphinates and phosphonates include—P(O)(R^(P))₂, wherein R^(P) is aliphatic, alkoxy, aryloxy,heteroaryloxy, (cycloaliphatic)oxy, (heterocycloaliphatic)oxy aryl,heteroaryl, cycloaliphatic or amino.

As used herein, an “aminoalkyl” refers to the structure(R^(X))₂N-alkyl-.

As used herein, a “cyanoalkyl” refers to the structure (NC)-alkyl-.

As used herein, a “urea” group refers to the structure—NR^(X)—CO—NR^(Y)R^(Z) and a “thiourea” group refers to the structure—NR^(X)—CS—NR^(Y)R^(Z) when used terminally and —NR^(X)—CO—NR^(Y)— or—NR^(X)—CS—NR^(Y)— when used internally, wherein R^(X), R^(Y), and R^(Z)have been defined above.

As used herein, a “guanidine” group refers to the structure—N═C(N(R^(X)R^(Y)))N(R^(X)R^(Y)) or —NR^(X)—C(═NR^(X))NR^(X)R^(Y)wherein R^(X) and R^(Y) have been defined above.

As used herein, the term “amidino” group refers to the structure—C═(NR^(X))N(R^(X)R^(Y)) wherein R^(X) and R^(Y) have been definedabove.

In general, the term “vicinal” refers to the placement of substituentson a group that includes two or more carbon atoms, wherein thesubstituents are attached to adjacent carbon atoms.

In general, the term “geminal” refers to the placement of substituentson a group that includes two or more carbon atoms, wherein thesubstituents are attached to the same carbon atom.

The terms “terminally” and “internally” refer to the location of a groupwithin a substituent. A group is terminal when the group is present atthe end of the substituent not further bonded to the rest of thechemical structure. Carboxyalkyl, i.e., R^(X)O(O)C-alkyl is an exampleof a carboxy group used terminally. A group is internal when the groupis present in the middle of a substituent of the chemical structure.Alkylcarboxy (e.g., alkyl-C(O)O— or alkyl-OC(O)—) and alkylcarboxyaryl(e.g., alkyl-C(O)O-aryl- or alkyl-O(CO)-aryl-) are examples of carboxygroups used internally.

As used herein, an “aliphatic chain” refers to a branched or straightaliphatic group (e.g., alkyl groups, alkenyl groups, or alkynyl groups).A straight aliphatic chain has the structure —[CH₂]_(v)—, where v is1-12. A branched aliphatic chain is a straight aliphatic chain that issubstituted with one or more aliphatic groups. A branched aliphaticchain has the structure —[CQQ]_(v)— where Q is independently a hydrogenor an aliphatic group; however, Q shall be an aliphatic group in atleast one instance. The term aliphatic chain includes alkyl chains,alkenyl chains, and alkynyl chains, where alkyl, alkenyl, and alkynylare defined above.

The phrase “optionally substituted” is used interchangeably with thephrase “substituted or unsubstituted.” As described herein, compounds ofthe invention can optionally be substituted with one or moresubstituents, such as are illustrated generally above, or as exemplifiedby particular classes, subclasses, and species of the invention. Asdescribed herein, the variables R₁, R₂, R₃, and other variablescontained in Formulae described herein encompass specific groups, suchas alkyl and aryl. Unless otherwise noted, each of the specific groupsfor the variables R₁, R₂, R₃, and other variables contained therein canbe optionally substituted with one or more substituents describedherein. Each substituent of a specific group is further optionallysubstituted with one to three of halo, cyano, oxo, alkoxy, hydroxy,amino, nitro, aryl, cycloaliphatic, heterocycloaliphatic, heteroaryl,haloalkyl, and alkyl. For instance, an alkyl group can be substitutedwith alkylsulfanyl and the alkylsulfanyl can be optionally substitutedwith one to three of halo, cyano, oxo, alkoxy, hydroxy, amino, nitro,aryl, haloalkyl, and alkyl. As an additional example, the cycloalkylportion of a (cycloalkyl)carbonylamino can be optionally substitutedwith one to three of halo, cyano, alkoxy, hydroxy, nitro, haloalkyl, andalkyl. When two alkoxy groups are bound to the same atom or adjacentatoms, the two alkoxy groups can form a ring together with the atom(s)to which they are bound.

In general, the term “substituted,” whether preceded by the term“optionally” or not, refers to the replacement of hydrogen radicals in agiven structure with the radical of a specified substituent. Specificsubstituents are described above in the definitions and below in thedescription of compounds and examples thereof. Unless otherwiseindicated, an optionally substituted group can have a substituent ateach substitutable position of the group, and when more than oneposition in any given structure can be substituted with more than onesubstituent selected from a specified group, the substituent can beeither the same or different at every position. A ring substituent, suchas a heterocycloalkyl, can be bound to another ring, such as acycloalkyl, to form a spiro-bicyclic ring system, e.g., both rings shareone common atom. As one of ordinary skill in the art will recognize,combinations of substituents envisioned by this invention are thosecombinations that result in the formation of stable or chemicallyfeasible compounds.

The phrase “stable or chemically feasible,” as used herein, refers tocompounds that are not substantially altered when subjected toconditions to allow for their production, detection, and preferablytheir recovery, purification, and use for one or more of the purposesdisclosed herein. In some embodiments, a stable compound or chemicallyfeasible compound is one that is not substantially altered when kept ata temperature of 40° C. or less, in the absence of moisture or otherchemically reactive conditions, for at least a week.

As used herein, an “effective amount” is defined as the amount requiredto confer a therapeutic effect on the treated patient, and is typicallydetermined based on age, surface area, weight, and condition of thepatient. The interrelationship of dosages for animals and humans (basedon milligrams per meter squared of body surface) is described byFreireich et al., Cancer Chemother. Rep., 50: 219 (1966). Body surfacearea may be approximately determined from height and weight of thepatient. See, e.g., Scientific Tables, Geigy Pharmaceuticals, Ardsley,New York, 537 (1970). As used herein, “patient” refers to a mammal,including a human.

Unless otherwise stated, structures depicted herein are also meant toinclude all isomeric (e.g., enantiomeric, diastereomeric, and geometric(or conformational)) forms of the structure; for example, the R and Sconfigurations for each asymmetric center, (Z) and (E) double bondisomers, and (Z) and (E) conformational isomers. Therefore, singlestereochemical isomers as well as enantiomeric, diastereomeric, andgeometric (or conformational) mixtures of the present compounds arewithin the scope of the invention. Unless otherwise stated, alltautomeric forms of the compounds of the invention are within the scopeof the invention. Additionally, unless otherwise stated, structuresdepicted herein are also meant to include compounds that differ only inthe presence of one or more isotopically enriched atoms. For example,compounds having the present structures except for the replacement ofhydrogen by deuterium or tritium, or the replacement of a carbon by a¹³C- or ¹⁴C-enriched carbon are within the scope of this invention. Suchcompounds are useful, for example, as analytical tools or probes inbiological assays, or as therapeutic agents.

Chemical structures and nomenclature are derived from ChemDraw, version11.0.1, Cambridge, Mass.

II. Commonly Used Abbreviations

The following abbreviations are used:

-   PG protecting group-   LG leaving group-   DCM dichloromethane-   Ac acetyl-   DMF dimethylformamide-   EtOAc ethyl acetate-   DMSO dimethyl sulfoxide-   MeCN acetonitrile-   TCA trichloroacetic acid-   ATP adenosine triphosphate-   EtOH ethanol-   Ph phenyl-   Me methyl-   Et ethyl-   Bu butyl-   DEAD diethylazodicarboxylate-   HEPES 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid-   BSA bovine serum albumin-   DTT dithiothreitol-   MOPS 4-morpholinepropanesulfonic acid-   NMR nuclear magnetic resonance-   HPLC high performance liquid chromatography-   LCMS liquid chromatography-mass spectrometry-   TLC thin layer chromatography-   Rt retention time-   HOBt hydroxybenzotriazole-   Ms mesyl-   Ts tosyl-   Tf triflyl-   Bs besyl-   Ns nosyl-   Cbz carboxybenzyl-   Moz p-methoxybenzyl carbonyl-   Boc tert-butyloxycarbonyl-   Fmoc 9-fluorenylmethyloxycarbonyl-   Bz benzoyl-   Bn benzyl-   PMB p-methoxybenzyl-   DMPM 3,4-dimethoxybenzyl-   PMP p-methoxyphenyl

III. Methods of Synthesizing Compounds of Formula I

One aspect of the present invention provides a novel synthesis forgenerating thiazolidine compounds that are useful for the treatment ofmetabolic disorders. This synthetic method is useful for preparing acompound of Formula I:

or a pharmaceutically acceptable salt thereof, wherein each of R₁ and R₂is independently selected from H, halo, aliphatic, and alkoxy, whereinthe aliphatic or alkoxy is optionally substituted with 1-3 of halo;comprising the step of:

converting a compound of Formula 2A into a compound of Formula I

wherein R₃ is hydrogen or an optionally substituted C₁₋₆ alkyl. In someembodiments, the compound of Formula 2A undergoes hydrolysis to generatea compound of Formula I. For example, the compound of Formula 2A istreated with an acid to generate the compound of Formula I. In otherexamples, the compound of Formula 2A is treated with an acid and heat togenerate a compound of Formula I.

In some embodiments, R₃ is methyl, ethyl, propyl, isopropyl, butyl, ortert-butyl, each of which is optionally substituted. In otherembodiments, R₃ is methyl, ethyl, propyl, isopropyl, butyl, ortent-butyl, each of which is unsubstituted. And, in some embodiments, R₃is hydrogen.

Some embodiments further comprise reacting a compound of Formula 3A witha compound of Formula 4A:

wherein X₁ is a leaving group (e.g., halo or triflyl), to generate thecompound of Formula 2A.

In some embodiments, the compound of Formula 4A comprises

In some embodiments, the compound of Formula 4A comprises

In some embodiments, the compound of Formula 4A comprises

In some embodiments, the compound of Formula 4A comprises

Some embodiments further comprise converting a compound of Formula 5A

wherein X₁ is a leaving group, to a compound of Formula 4A.

In some embodiments, X₁ is a halo (e.g., Cl or Br) or triflyl group. Insome embodiments, the compound of Formula 5A is treated with a reagentR₃ONH₂.Cl, wherein R₃ is defined above. In some examples, the reagentcomprises HONH₂.HCl, TMSNHOTMS, (H₂NOH)₂.H₂SO₄, CH₃ONH₂.HCl, or anycombination thereof to generate a compound of Formula 4A.

In some embodiments, the compound of Formula 5A comprises

wherein X₁ is Cl or Br.

Some embodiments further comprise converting a compound of Formula 6A

to a compound of Formula 5A. For example, the compound of Formula 6Aundergoes halogenation to generate a compound of Formula 5A.

In some embodiments, the compound of Formula 6A comprises

wherein R₁ is selected from a C₁₋₆ alkyl or C₁₋₆ alkoxy, either of whichis optionally substituted with 1-3 halo, and R₂ is —H or halo.

In some embodiments, R₁ is a C₁₋₆ alkyl optionally substituted with 1-3halo. For example, R₁ is selected from methyl, ethyl, or propyl, any ofwhich is optionally substituted with 1-3 halo.

In other embodiments, the compound of Formula 6A comprises

Some embodiments further comprise reacting the compound

with the compound

under condensation conditions to form a compound of Formula 3B

Other embodiments further comprise reducing the compound of Formula 3Bto generate a compound of Formula 3A

Another aspect of the present invention provides a novel synthesis forgenerating a compound of Formula I:

or a pharmaceutically acceptable salt thereof, wherein each of R₁ and R₂is independently selected from H, halo, aliphatic, and alkoxy, whereinthe aliphatic or alkoxy is optionally substituted with 1-3 of halo;comprising the step of:

converting a compound of Formula 2A into a compound of Formula I

wherein R₃ is hydrogen or an optionally substituted C₁₋₆ alkyl. In someembodiments, the compound of Formula 2A undergoes hydrolysis to generatea compound of Formula I. For example, the compound of Formula 2A istreated with an acid to generate the compound of Formula I. In otherexamples, the compound of Formula 2A is treated with an acid and heat togenerate a compound of Formula I.

In some embodiments, R₃ is methyl, ethyl, propyl, isopropyl, butyl, ortert-butyl, each of which is optionally substituted. In otherembodiments, R₃ is methyl, ethyl, propyl, isopropyl, butyl, ortert-butyl, each of which is unsubstituted. And, in some embodiments, R₃is hydrogen.

Some embodiments further comprise converting a compound of Formula 7Ainto a compound of Formula 2A:

In some embodiments, the compound of Formula 7A is converted to acompound of Formula 2A under reduction conditions. For example, thecompound of Formula 2A is generated by treating the compound of Formula7A with a reducing reagent comprising NaBH₄ (e.g., NaBH₄ and CoCl₂).

In some embodiments, the compound of Formula 7A comprises

Some embodiments further comprise reacting a compound of Formula 8A

with the compound

to generate a compound of Formula 7A.

In some embodiments, the compound of Formula 8A is reacted with thecompound

under condensation conditions. For example, the compound of Formula 8Ais reacted with the compound

in the presence of an acid (e.g., benzoic acid) and heat.

In some embodiments, the compound of Formula 8A comprises

Some embodiments further comprise reacting a compound of Formula 4A, asdefined above, with the compound

to generate a compound of Formula 8A.

Some embodiments further comprise converting a compound of Formula 5A

wherein X₁ is a leaving group, to a compound of Formula 4A.

In some embodiments, X₁ is a halo (e.g., Cl or Br) or triflyl group. Insome embodiments, the compound of Formula 5A is treated with a reagentof the general formula R₃ONH₂.HCl or (R₃ONH₂)₂.H₂SO₄, wherein R₃ isdefined above. In some instances, R₃ONH₂ comprises HONH₂, TMSNHOTMS,CH₃ONH₂, CH₃CH₂ONH₂, or any combination thereof to generate a compoundof Formula 4A.

In some embodiments, the compound of Formula 5A comprises

wherein X₁ is Cl or Br.

Some embodiments further comprise converting a compound of Formula 6A

to a compound of Formula 5A. For example, the compound of Formula 6Aundergoes halogenation to generate a compound of Formula 5A.

In some embodiments, the compound of Formula 6A comprises

wherein R₁ is selected from a C₁₋₆ alkyl or C₁₋₆ alkoxy, either of whichis optionally substituted with 1-3 halo, and R₂ is —H or halo.

In some embodiments, R₁ is a C₁₋₆ alkyl optionally substituted with 1-3halo. For example, R₁ is selected from methyl, ethyl, or propyl, any ofwhich is optionally substituted with 1-3 halo.

In other embodiments, the compound of Formula 6A comprises

IV. Exemplary Syntheses

The following synthetic schemes illustrate some examples of methods forgenerating compounds of Formula I according to the present invention.

wherein R₁, R₂, R₃, and X₁ are defined above.

A compound of Formula I can be synthesized according to Scheme 1,wherein a thiazolidine-2,4-dione of Formula 3A is alkylated by analkoxylimine of Formula 4A to form a compound of Formula 2A, wherein X₁is a leaving group such as halo, tosyl, mesyl, or trifluoromethanesufonyl. The alkylation can be accomplished under basic conditions.Exemplary solvents are polor aprotic solvents such as DMSO or DMF, andthe base can be a strong base, such as potassium tert-butoxide. Theintermediate 2A is treated with an acid (e.g., 6M HCl in acetic acid) togenerate a compound of Formula I. This transformation can also beperformed under elevated temperatures.

In some embodiments, the compound of Formula 3A is generated accordingto Scheme 1A:

A compounds of Formula 3A can be synthesized according to Scheme 1A,wherein 4-hydroxybenzaldehyde is condensed with thiazolidine-2,4-dioneunder Knoevenagel conditions to produce(E)-5-(4-hydroxybenzylidene)thiazolidine-2,4-dione. This intermediatecan then be reduced to the compound of Formula 3A by, for example,hydrogenation.

In several embodiments, the compound of Formula 4A is formed accordingto Scheme 1B:

The synthesis of intermediate 4A can be accomplished first byacetylation of a 2-pyridyl lithium species produced from contacting a2-bromopyridine species with n-butyllithium, with an appropriateacetamide compound. The resulting acetyl compound, having anotherbromine substituent, can then be coupled with an unsubstituted C₁₋₃alkyl substituent using a palladium catalyst to generate theintermediate compound 6A. Halogenation of the alpha position ofintermediate 6A using a molecular halogen compound provides thehalogenated intermediate compound 5A. Compound of Formula 4A can then beproduced by exposure of 5A with the appropriate alkoxylamine compoundunder acidic alcoholic conditions. An example of the production of acompound of Formula 4A from a compound of Formula 5A is provided inScheme 1 C. As shown in the scheme, treatment of a compound of Formula5A, wherein X is Br, with O-alkoxylamine hydrochloride in ethanolprovides a compound of Formula 4A.

In other embodiments, the compound of Formula I is generated accordingto Scheme 2.

wherein R₁, R₂, R₃, and X₁ are defined above.

4-hydroxybenzaldehyde is first alkylated by an alkoxylimine of Formula4A to provide intermediate 8A. Enol condensation of a compound ofFormula 4A with thiazolidine-2,4-dione under acidic conditions usingpyrrolidine as the solvent provides a compound of Formula 7A. Furtherreduction of the olefin using cobalt chloride and sodium borohydrideprovides a compound of Formula 2A, which can be converted to the ketoneusing an acid such as glyoxylic acid or pyruvic acid at elevatedtemperatures.

V. Novel Compounds

Another aspect of the present invention provides a compound of Formula10A, 10B, or 10C

wherein R₁ is halo, C₁₋₆ alkyl optionally substituted with 1-3 halo, orC₁₋₆ alkoxy optionally substituted with 1-3 halo; R₃ is hydrogen orunsubstituted C₁₋₆ alkyl; and X_(A) is a leaving group or hydrogen.

In several embodiments, R₃ of Formula 10A, 10B, or 10C is hydrogen. Inother embodiments, R₃ of Formula 10A, 10B, or 10C is methyl, ethyl,propyl, isopropyl, butyl, or tert-butyl, each of which is unsubstituted.

Another aspect of the present invention provides a compound of Formula10D, 10E, or 10F

wherein R₁ and X_(A) are defined above.

Another aspect of the present invention provides a compound Formula11A-11M

wherein X_(A) and R₃ are defined above.

In some embodiments, X_(A) is a leaving group selected from —Br, —Cl,—I, —OMs, —OTs, —OTf, —OBs, —ONs, —O-tresylate, or —OPO(OR₄)₂, whereineach R₄ is independently C₁₋₄ alkyl or two of R₄ together with theoxygen and phosphorous atoms to which they are attached form a 5-7membered ring. In other embodiments, X_(A) is hydrogen.

Another aspect of the present invention provides a compound of Formula2A

wherein each of R₁, R₂, and R₃ is defined above. For example, in oneembodiment, the compound of Formula 2A comprises

And, another aspect of the present invention provides a compoundselected from

wherein R₃ is defined above.

VI. EXAMPLES Example 1 Preparation of 1-(5-bromopyridin-2-yl)ethanone

In a 3-neck 1000 ml round bottom flask, 2,5-dibromopyridine (10.0 g,42.2 mmol) was dissolved in toluene (400 ml) and cooled to −40 ° C.(CH₃CN/dry ice). 1.6 M of n-butyllithium in tetrahydrofuran (26.38 mL,42.21 mmol) was slowly added to the cooled solution to form a deepreddish solution, which was stirred at −40° C. for 40 minutes.N,N-Dimethylacetamide (7.14 mL, 76.8 mmol) was added with no discernablechange. The mixture was allowed to slowly warm to room temperature.Then, the mixture was quenched by adding 25 ml sat'd ammonium chloride.Added 100 ml H₂O and extracted with EtOAc (250 ml). The organic phasewas washed with water (200 ml). The combined aqueous phases wereextracted with EtOAc (100 ml). The combined organic extracts were washedwith brine, dried (Na₂SO₄), filtered and evaporated in vacuo to generate6.31 g of a tan solid. ¹H-NMR (CDCl₃): δ 8.74 (d, J=1.9 Hz, 1H), 7.96(m, 2H), 2.70 (s, 3H). HPLC: RT=3.237 min., 60 area %@210 nm; RT=3.238min., 87 area %@254 nm. LCMS: MS (ESI-) for C₈H₇BrO m/z 201.0 (M+H)⁺.

Example 2 Preparation of (1-(5-ethylpyridin-2-yl)ethanone

A mixture of 1-(5-bromopyridin-2-yl)ethanone (6.30 g, 31.5 mmol;Supplier=Kalexsyn; Lot=90) and[1,1′-Bis(diphenylphosphino)ferrocene]dichloropalladium(II) (560 mg,0.76 mmol) in dioxane (120 ml) was degassed by sparging with N₂ for 10minutes. Added a solution (15% w/w) of diethyl zinc in hexane (50 ml)slowly, dropwise and heated to 50° C. The orange mixture turned dark,ultimately generating a dark orange with yellow solids as it stirred at50° C. for 30 minutes. Allowed to cool to room temperature. The reactionmixture was partitioned between EtOAc (200 ml) and water (200 ml), andthe aqueous phase was extracted 2× with EtOAc. The combined organicphases were washed with brine (500 ml), dried (Na₂SO₄), filtered andevaporated in vacuo to give 4.14 g brown oil. Distilled under high vacusing short-path distillation apparatus. BP=55° C.@0.32 torr to give2.249 g of slightly tinted oil. ¹H-NMR (CDCl₃): δ 8.50 (d, J=1.9 Hz,1H), 7.96 (d, J=7.9 Hz, 1H), 7.63 (dd, J=8.0, 2.2 Hz, 1H), 2.71 (m, 2H),2.69 (s, 3H), 1.27 (t, J=7.6 Hz, 3H). HPLC: 2.011 min., 57 area %@210nm;2.012 min., 75 area %@254 nm. LCMS: MS (ESI-) for C₁₀H₁₂O m/z 150.1(M+H)⁺.

Example 3 Preparation of 22-bromo-1-(5-ethylpyridin-2-yl)ethanonehydrogen bromide

To a stirring solution of 1-(5-ethylpyridin-2-yl)ethanone (634 mg, 4.25mmol; Supplier =Kalexsyn; Lo=1003-TTP-112) in 33% HBr/HOAc (w/w, 5 ml)at 10° C. (water bath with a little ice) was added 0.173 ml brominedropwise. Stirred for 1 hour at room temperature at which time thereaction appeared complete by HPLC. Added ether (5 ml) and stirred for15 minutes. The orange solids were collected by suction filtration,washed with ether, and dried under high vac. 1.042 g orange solid.¹H-NMR (DMSO-d6): δ 9.65(brs, 1H), 8.62 (d, J=1.9 Hz, 1H), 7.97 (m, 1H),7.91 (d, J=2.1 Hz, 1H), 4.99 (s, 2H), 2.74 (q, J=7.5 Hz, 2H), 1.22 (t,J=7.6 Hz, 3H). HPLC: 3.747 min., 83 area %@2540 nm; 3.747 min., 95 area%@210 nm. MS (ESI-) for C₉H₁₀BrNO m/z 229.1 (M+H)⁺.

Example 4 Preparation of 2-bromo-1-(5-ethylpyridin-2-yl)ethanoneO-methyl oxime

To a stirring solution of 2-bromo-1-(5-ethylpyridin-2-yl)ethanonehydrobromide (1.024 g, 3.314 mmol; Supplier=Kalexsyn; Lot=1003-TTP-185)in EtOH (10 ml) was added methoxylamine hydrochloride (553.5 mg, 6.628mmol). Left to stir at RT overnight. The reaction mixture was evaporatedin vacuo. The residue was dissolved in DCM and an equal volume ofsaturated NaHCO₃ was added and the biphasic mixture stirred for 30minutes. The phases were separated and the aqueous phase was extractedwith DCM. The combined organic phases were dried (Na₂SO₄), filtered andevaporated in vacuo to afford a pale yellow oil which crystallized uponstanding. ¹H-NMR (CDCl₃): δ 8.50 (s, 1H), 7.87 (d, J=8.3 Hz, 1H), 7.59(m, 1H), 4.79 (s, 1H), 4.64 (s, 1H), 4.13 (d, J=4.4 Hz, 3H), 2.70 (q,J=7.7 Hz, 2H), 1.28(t, J=7.7 Hz, 3H). HPLC: 3.429 min., 30 area % and3.621 min., 31 area %@210 nm; 3.414 min., 36 area % and 3.618 min., 36area %@210 nm. MS (ESI-) for C₁₀H₁₃BrN₂O m/z 258.2 (M+H)⁺.

Example 5 Preparation of5-(4-(2-(5-ethylpyridin-2-yl)-2-(methoxyimino)ethoxy)benzyl)thiazolidine-2,4-dione

To a stirring solution of 5-(4-hydroxybenzyl)thiazolidine-2,4-dione (210mg, 0.941 mmol) in DMSO was added potassium tert-Butoxide (227 mg, 2.02mmol) in a single portion. Stirred at RT for 15 minutes. Added asolution of (1Z)-2-bromo-1-(5-ethylpyridin-2-yl)ethanone O-methyloxime(242 mg, 0.941 mmol; Supplier=Kalexsyn; Lot=1003-TTP-186) in DMSO (2ml). Added 1M HCl until pH of mixture was about 3. Extracted with EtOAc.The extract was washed with water, dried (Na₂SO₄), filtered andevaporated in vacuo to give an off-white foam. 278 mg. ¹H-NMR (DMSO-d6):δ 12.05 (brs, 1H), 8.47 (d, J=1.7 Hz, 1H), 7.77 (m, 1H), 7.70m, 1H),7.14 (d, J=8.5 Hz, 2H), 6.90 (d, J=8.5 Hz, 2H), 5.17 (s, 2H), 4.87 (dd,J=8.9, 4.4 Hz, 1H), 4.01 (s, 3H), 3.30 (dd, J=14.2, 4.5 Hz, 1H), 3.06(dd, J=14.1, 9.1 Hz, 1H), 2.64 (q, J=7.7 Hz, 2H), 1.19 (t, J=7.6 Hz,3H). HPLC: 3.103 min., 82area % and 3.379 min., 18 area %@254 nm; 3.109min., 91 area % and 3.379 min., 9area %@254 nm. MS (ESI-) forC₂₀H₂₁N₃O₄S m/z 400.3 (M+H)⁺. m/z 398.3 (M−H)⁻

Example 6 Preparation of5-(4-(2-(5-ethylpyridin-2-yl)-2-oxoethoxy)benzyl)thiazolidine-2,4-dione

A stirring solution of5-(4-{[(2Z)-2-(5-ethylpyridin-2-yl)-2-(methoxyimino)ethyl]oxy}benzyl)-1,3-thiazolidine-2,4-dione(81 mg, 0.20 mmol; Supplier=Kalexsyn; Lot=1003-TTP-194) in 6M HCl (2 ml)and pyruvic acid (0.5 ml) was heated at 75° C. After 2 h at 75° C. HPLCshowed reaction was complete. Neutralized with sat'd NaHCO₃ andextracted with EtOAc. Extract dried (Na₂SO₄), filtered and evaporated invacuo to give 45 mg (60%) pale yellow oil. ¹H-NMR (DMSO-d6): δ 12.02(brs, 1H), 8.64 (s, 1H), 7.91 (m, 1H), 7.14 (d, J=8.5 Hz, 2H), 6.88 (d,J=8.5 Hz, 2H), 5.66 (s, 2H), 4.87 (dd, J=9.2, 4.3 Hz, 1H), 3.31 (m, 1H),3.05 (dd, J=14.1, 9.1 Hz, 1H), 2.74 (q, J=7.7 Hz, 2H), 1.23 (t, J=7.7Hz, 3H). HPLC (3.860 min., 100 area %@210 and 254 nm. MS (ESI-) forC₁₉H₁₈N₂O₄S m/z 371.3 (M+H)⁺; m/z 369.4 (M−H)⁻

Example 7 Assays

Assays for Measuring Reduced PPARγ Receptor Activation

Whereas activation of the PPARγ receptor is generally believed to be aselection criteria to select for molecules that may have anti-diabeticand insulin sensitizing pharmacology, this invention finds thatactivation of this receptor should be a negative selection criterion.Molecules will be chosen from this chemical space because they havereduced, not just selective, activation of PPARγ. The optimal compoundshave at least a 10-fold reduced potency as compared to pioglitazone andless than 50% of the full activation produced by rosiglitazone in assaysconducted in vitro for transactivation of the PPARγ receptor. The assaysare conducted by first evaluation of the direct interactions of themolecules with the ligand binding domain of PPARγ. This can be performedwith a commercial interaction kit that measures the direct interactionby florescence using rosiglitazone as a positive control. Further assayscan be conducted in a manner similar to that described by Lehmann et al.[Lehmann J M, Moore L B, Smith-Oliver T A: An AntidiabeticThiazolidinedione is a High Affinity Ligand for PeroxisomeProliferator-activated Receptor (PPAR) J. Biol. Chem.(1995) 270: 12953]but will use luciferase as a reporter as in Vosper et al. [Vosper, H.,Khoudoli, G A, Palmer, C N (2003) The peroxisome proliferators activatedreceptor d is required for the differentiation of THP-1 moncytic cellsby phorbol ester. Nuclear Receptor 1:9]. Compound stocks will bedissolved in DMSO and added to the cell cultures at final concentrationsof 0.1 to 100 μM and the relative activation will be calculated asinduction of the reporter gene (luciferase) as corrected for by theexpression of the control plasmid (coding for galactosidase).Pioglitazone and rosiglitazone will be used as reference compounds asdescribed above.

In addition to showing the reduced activation of the PPARγ receptor invitro, the compounds will not produce significant activation of thereceptor in animals. Compounds dosed to full effect for insulinsensitizing actions in vivo (see below) will be not increase activationof PPARγ in the liver as measured by the expression of a P2, a biomarkerfor ectopic adipogenesis in the liver [Matsusue K, Haluzik M, Lambert G,Yim S-H, Oksana Gavrilova O, Ward J M, Brewer B, Reitman M L, Gonzalez FJ. (2003) Liver-specific disruption of PPAR in leptin-deficient miceimproves fatty liver but aggravates diabetic phenotypes. J. Clin.Invest.; 111: 737] in contrast to pioglitazone and rosiglitazone, whichdo increase a P2 expression under these conditions.

The insulin sensitizing and antidiabetic pharmacology are measured inthe KKA^(Y) mice as previously reported [Hofmann, C., Lornez, K., andColca, J. R. (1991). Glucose transport deficiency corrected by treatmentwith the oral anti-hyperglycemic agent Pioglitazone. Endocrinology,129:1915-1925]. Compounds are formulated in 1% sodium carboxymethylcellulose, and 0.01% tween 20 and dosed daily by oral gavage.After 4 days of once daily treatment, treatment blood samples are takenfrom the retro-orbital sinus and analyzed for glucose, triglycerides,and insulin as described in Hofmann et al. Doses of compounds thatproduce at least 80% of the maximum lowering of glucose, triglycerides,and insulin will not significantly increase the expression of a P2 inthe liver of these mice.

Other Embodiments

It is to be understood that while the invention has been described inconjunction with the detailed description thereof, the foregoingdescription is intended to illustrate and not limit the scope of theinvention, which is defined by the scope of the appended claims. Otheraspects, advantages, and modifications are within the scope of thefollowing claims.

1-38. (canceled)
 39. A compound selected from

wherein R₃ is hydrogen or an unsubstituted C₁₋₆ alkyl.
 40. The compoundof claim 39, wherein R₃ is an unsubstituted C₁₋₆ alkyl.
 41. The compoundof claim 40, wherein R₃ is methyl, ethyl, propyl, isopropyl, butyl, ortert-butyl, each of which is unsubstituted.
 42. (canceled)